Technical Field
The subject matter includes flexible but strong dies that can be used as dies for forming large extrusions, sheets and the like, of small curvature, the curvature of the dies being controllable by the application of much larger actuation forces and moments than the die forces and moments arising from the forming process.
Background Art
Metal forming dies, such as dies used for stretch forming of extrusions and sheets, are usually single monolithic pieces made of metals, plastics, wood, etc. The die geometry is fixed during the process of fabrication of the die. The shape of the dies is imposed on the part by the forming process. However, a separate die of the appropriate geometry is required for forming each part.
Recently, reconfigurable dies made up of an array of hydraulic cylinders which help define the position of the sheet are known. However, these use an interpolating layer of urethane which is flexible enough that it only serves to smooth out the bumps that would be produced by the hemispherical surfaces on the ends of the cylinders. The interpolating layer is not strong enough to define the geometry over a free length, and support the forming loads experienced over this length.